The major goal of the proposed research is to establish the molecular structure of respiratory mucus glycoproteins and to elucidate the nature of intermolecular crosslinks and their functional significance. In close collaboration between rheological and chemical laboratories, the study will be carried out primarily on canine tracheal pouch preparation. After solubilizing the mucus secretions with sodium dodecyl sulfate and/or mercaptoethanol, and using gel electrophoretic and chromatographic methods major components of mucus secretions will be fractionated and chemically characterized with a special emphasis on the localization of cysteine residues in the isolated components. Attempts will then be made to reconstitute the mucus gel from isolated components of mucus secretions. At each step of these investigations, the process of solubilization and reconstitution of mucus gel, in particular, will be evaluated by rheological methods and correlated with chemical data. Such an integrated approach will provide basic information about the nature and function of intermolecular interactions and crosslinks among the major components of mucus secretions.